<template>
    <div class="list" ref="wrapper">
        <div>
            <div class="area">
                <div class="title border-topbottom">当前城市</div>
                <div class="button-list">
                    <div class="button-wrapper">
                        <div class="button">{{this.currentCity}}</div> 
                    </div>
                </div>
            </div>
            <div class="area">
                <div class="title border-topbottom">热门城市</div>
                <div class="button-list">
                    <div class="button-wrapper"  v-for="item in hot" :key="item.id" @click="handleCityClick(item.name)">
                        <div class="button">{{item.name}}</div> 
                    </div>  
                </div>
            </div>
            <!-- 对象也可以循环。第2个值为 key   数组第2个值为  index -->
            <!-- 为什么ref前面要加： 因为不加的话，key就不是变量，只是一个普通字符串。 -->
            <div class="area" v-for="(item, key) in cities" :key="key" :ref="key">
                    <div class="title border-topbottom">{{key}}</div>
                    <div class="item-list">
                        <div class="item border-bottom" v-for="innerItem of item" :key="innerItem.id" @click="handleCityClick(innerItem.name)">
                                {{innerItem.name}}
                        </div>
                    </div>
            </div>  
      </div>
    </div>

</template>
<script>
import BScroll from 'better-scroll'
import { mapState, mapMutations } from 'vuex'
export default {
    name:'CityList',
    props:{
        hot:Array,
        cities:Object,
        letter:String
    },
    methods: {
        handleCityClick(city){
            // this.$store.commit('changeCity',city)
            this.changeCity(city)
                // 当选择城市之后自动跳转到主页
             this.$router.push('/')
             
        },
        ...mapMutations(['changeCity'])
    },
    computed: {
        ...mapState({
            currentCity:'city'
        })
    },
    mounted() {
        // this.$refs 获取dom元素
        this.scroll= new BScroll(this.$refs.wrapper)
    },
    watch: {
        letter(){
            // 作用：滚动到指定的目标元素。当点击A，就对应滚动到以A开头的城市。
            if(this.letter){
                // 获取到key值对应的城市区域
                const element=this.$refs[this.letter][0]
               this.scroll.scrollToElement(element)
            }
          
            // console.log(this.letter)
        }
    },
}
</script>
<style lang="stylus" scoped>
@import '~styles/varibles.styl';
    .border-topbottom
    &:before
        border-color:#ccc
    &:after
        border-color:#ccc
     .border-bottom
    &:before
        border-color:#bbb
    .list
        overflow :hidden
        position :absolute
        //空出头部和搜索框的位置---2倍图原理
        top:1.58rem
        left:0
        right :0
        bottom :0
        .title
            height :.54rem
            line-height :.44rem
            background-color :#eee
            padding-left:.2rem
            color :#666
            font-size :.26rem
        .button-list
            overflow :hidden
            padding :.1rem .6rem .1rem .1rem
        .button-wrapper
            float :left
            width : 33.33%
            .button
                margin :.1rem
                padding:.1rem 0
                text-align :center
                border :.02rem solid #ccc
                border-radius :.06rem
        .item-list
            .item
                line-height :.76rem
                padding-left :.2rem

</style>
